Hello Hello
I can also press these buttons directly. The picture is not correct. Can send a photo if required.
Greetings Walter

The keyboard is available for different languages and layouts.
A QWERTY keyboard (Z to the right of the T) also has ÖÄÜ on it. If these letters do not appear when these keys are pressed, then the keyboard layout in the PC is not correct. You must set this in the control panel under "Language" ("Keyboard layout: German").
These umlauts do not appear on a QWERTY keyboard (Y to the right of the T). However, you can switch this English keyboard to German (in the language settings), and then ÖÄÜ will also be on the English keyboard where they are on the German keyboard. You should then place stickers over the corresponding keys.

Hello, my MK540 set included the K540 keyboard and the M310 mouse. The assignment of the keys corresponds to the normal German keyboard. So everything is in the usual place.

Hello Walter
Many thanks for the quick reply. Yes please, send a photo if possible.
Greetings, Karli